US president Barack Obama has appointed vice president Joe Biden to head an effort to curb gun violence in the aftermath of the Connecticut primary school massacre.

Mr Obama set up a task force to frame "concrete proposals" on ending mass shootings by next month and called for new laws, but denied he had been on "vacation" on gun control.

The president said a majority of Americans back changes to some laws, but acknowledged the debate will stir deep passions.

He has declared that while he backs the right to bear arms, it must be within responsible limits.

"There is a big chunk of space between what, you know, the Second Amendment means and having no rules at all," he said.

He also called for new laws to ensure background checks for all gun purchases and signalled an effort to expand mental health care, in an effort to deter psychologically troubled people from turning to mass violence.

"We're going to need to work on making access to mental health care at least as easy as access to a gun. We're going to need to look closely at a culture, that, all too often, glorifies guns and violence," he said.

"And any actions we must take must begin inside the home and inside our hearts."

Mr Obama, who failed to put political muscle behind greater gun control after previous mass slaughters, dismissed the notion that the task force would simply be a familiar, toothless Washington policy commission with little impact.

And he said killings of 20 children aged six and seven and six teachers and caregivers in the elementary school in Newtown were so horrific they should provide lawmakers with a potent incentive for action, even when the initial shock fades.

"I would hope that our memories aren't so short that what we saw in Newtown isn't lingering with us, that we don't remain passionate about it only a month later," Mr Obama said at the White House.

"This is a team that has a very specific task to pull together real reforms right now.

"I will be putting forward very specific proposals. I will be talking about them in my State of the Union, and we will be working with interested members of Congress to try to get something done."

'I don't think I've been on vacation'

Mr Obama, who comforted relatives of Newtown victims on Sunday, bristled when asked by a reporter whether he had been absent on gun control issues, following mass killings in Colorado, Arizona and Texas on his watch.

"I've been president of the United States, dealing with the worst economic crisis since the Great Depression, an auto industry on the verge of collapse, two wars. I don't think I've been on vacation," he said.

Mr Obama urged the slow moving Congress to hold timely votes on banning military-style assault weapons like the one used by gunman Adam Lanza in Newtown, and also on outlawing the sale of high-capacity ammunition clips.

He also called on the National Rifle Association, the most powerful gun lobby group which piles pressure on lawmakers over gun rights, to consider its priorities, before senior figures hold a news conference on Friday.

"The NRA is an organisation that has members who are mothers and fathers, and I would expect that they've been impacted by this as well, and hopefully they'll do some self-reflection."

Mr Biden has a history of framing crime legislation from his years in the Senate, has an affinity with law enforcement services, and also enjoys the kind of cordial links with many top Republicans in Congress that Mr Obama lacks.

The aftermath of the horrific shootings in Connecticut has prompted some pro-gun figures on Capitol Hill to admit that more needs to be done to regulate the sale and use of firearms.

One such politician is Democratic senator Joe Manchin of West Virginia.

The gun rights advocate said he would now be open to more regulation of military-style rifles like the one used in Newtown.

Mr Obama spoke with him on Tuesday (local time), the White House said.

But most evidence of shifting positions has been among Democrats, and there are signs that Republicans, especially those from rural, southern and conservative states may balk at new legislative action.

Meanwhile, the family of Sandy Hook Elementary principal Dawn Hochsprung invited mourners to visit at a local funeral home on Wednesday afternoon, though the burial was due to be private at an undisclosed time.

Another of the teachers, Victoria Soto, was among those to be buried at a funeral on Wednesday.

Funerals were also scheduled for six-year-old Charlotte Bacon, seven-year-old Daniel Barden and six-year-old Caroline Previdi, while the family of seven-year-old Chase Kowalski invited mourners to a public visitation and prayer vigil.

The surviving children from Sandy Hook Elementary faced another day at home as school authorities and parents made plans for an eventual return to a different location - the unused Chalk Hill School in nearby Monroe, where a sign across the street read, "Welcome Sandy Hook Elementary!"

At Sandy Hook itself, well wishers and mourners had left tributes such as candles, flowers and stuffed animals as police continued their investigations inside.

They have said the investigation could take months and have revealed nothing yet about Lanza's motive.